Endodontic Rotary Instruments Made From Hollow Tubes and Methods of Manufacturing Thereof

ABSTRACT

A hollow endodontic instrument having: a file axis; a proximal end; a tip; and a shaft portion between the proximal end and the tip; wherein the shaft portion defines a hollow void at least partially bounded by a plurality of fingers and a plurality of longitudinal spacings, each finger extends from the proximal end and includes an outer surface and an inner surface extending between longitudinal opposing walls; and wherein a portion of at least one of the longitudinal opposing walls includes a cutting edge.

RELATED DOCUMENTS

This is a continuation of U.S. application Ser. No. 13/404,570, filed onFeb. 24, 2012, which claims the benefit of priority U.S. provisionalapplication Ser. No. 61/446,251, filed Feb. 24, 2011 and U.S.provisional application Ser. No. 61/446,314, filed Feb. 24, 2011, whichare herein incorporated by reference for all purposes.

FIELD OF INVENTION

The present invention is directed to a method for manufacturing a dentalinstrument, and specifically to a rotary file useful for shaping andcleaning root canals.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 7,713,059 discusses an instrument used for cleaning and/orshaping a channel that exists in or through a solid object. It isdesigned to shape the channel 3 dimensionally by having the outercontour change as a result of the forces exerted upon it. The downsideto this design is that it can only be used with a motor driving thedesign up and down along the axis of the object. Furthermore, thisdesign does not rotate. For endodontic applications, a majority of themotors available in the dentist office only has rotation ability. Thiscauses the doctor to invest in a new motor. Also, the ability of thisdesign to perform a cut is allowed by changing the surface texture (i.e.roughening the outer surface) to engage and cut into the material (e.g.,shaving the root canal at a high speed as it changes shape). Lastly, themethod of manufacturing this design is very similar to stents made forthe cardiovascular industry where a laser cut of a cylindrical tube iscreated, which is a very time consuming and costly process. Therefore,the cost of the instrument is much higher than conventional rotary fileinstruments (approximately 7 times higher).

U.S. Pat. Nos. 6,890,134 and 5,941,760 generally discuss the commonprocess of manufacturing an endodontic rotary file through a grindingprocedure. U.S. Pat. No. 6,368,107 shows a design of having a crossingpattern which is similar to the design being shown in the applicationbut the process they have described would not allow the rotary file tochange geometry as a result of the forces exerted upon it.

SUMMARY OF THE INVENTION

The present invention provides an improved endodontic instrument, and/ormethod for making an endodontic instrument. In one aspect of the presentinvention, the method for manufacturing the endodontic instruments(e.g., rotary file) from a hollow core portion (e.g., a tube, cylinder,or otherwise). In another aspect of the present invention, theendodontic instrument may incorporate a straight taper, a varied taper,or any combination thereof (e.g., from the tip portion of the instrumentto the shank portion of the instrument or portions therebetween).

In another aspect of the present invention is to provide a new rotaryinstrument design that is able to change the outer contour of a rootcanal based on the forces exerted upon it. In doing so, may enable thisnew design to be used in a traditional rotary application such that thedentist may not have to purchase a new motor. In another aspect of thepresent invention, the new design may not require the addition ofroughened surfaces to create a cutting edge. In another aspect of thepresent invention, this new method of manufacturing may be employedthrough a photochemical machining process. In another aspect of thepresent invention, the design may have a variable cross-section throughthe ribs thus creating an aggressive outer surface for cutting, butoptionally a thicker more stable surface for the inside. In anotheraspect of the invention, the method for manufacturing the new rotaryfile design may comprise one at least of of: providing a sheet (e.g.,flat sheet) of Nitinol, Stainless, other material, or combinationsthereof (e.g., to be photochemically machined); stamping the sheet tothe desired geometry based on the finished file design; rolling thestamped (flat) sheet into the finished geometry; welding (e.g., laser orotherwise type welding) (e.g., at the seam) to complete the finishedpart; and combination thereof. This process is much less expensive butstill allows the benefits of a compressible rotary file.

In another aspect, the present invention contemplates a method formanufacturing a hollow instrument comprising the steps of: providing ahollow tube having a longitudinal tube axis; forming at least oneopening along a shaft portion of the hollow tube following apredetermined pattern thereby defining a plurality of fingers; anddeforming at least a portion of the hollow tube into a desired shape;and optionally joining at least two fingers along a portion of theopening to secure the hollow tube in the desired shape thereby formingthe hollow instrument.

In another aspect, the present invention contemplates a method formanufacturing a hollow instrument comprising the steps of: providing asheet of material; chemically milling the sheet to form a plurality ofopenings by remove material following a predetermined pattern, themilled sheet having at least two opposing edges; rolling the milledsheet into a desired tubular geometry; and joining a portion of the atleast two opposing edges to secure the desired tubular geometry therebyforming the hollow instrument.

In another aspect, the present invention contemplates a hollowinstrument comprising a tube axis, a proximal end and a tip with a shaftportion therebetween; the shaft portion defining a hollow void at leastpartially bounded by a plurality of fingers and a plurality oflongitudinal spacings, each finger extending from the proximal end,wherein the plurality of fingers converge at the tip such that there iscontact between at least two fingers for joining to one another by atleast one binding.

In another aspect, the present invention contemplates a hollowinstrument comprising a tube axis, a proximal end and a tip with a shaftportion therebetween; the shaft portion defining a hollow void at leastpartially bounded by a matrix of channels and a plurality of openingstherebetween, the matrix extending from the proximal end and convergesat the tip, wherein the channels extends is a opposing spiralorientations thereby crossing one to form the plurality of openings.

In yet another aspect, any of the aspects of the present invention maybe further characterized by one or any combination of the followingfeatures: a plurality of longitudinal openings are formed along theshaft portion of the hollow tube defining at least three fingersradially spaced from the tube axis; a first longitudinal opening extendsbetween a first finger and a second finger, a second longitudinalopening extends between the second finger and a third finger, and athird longitudinal opening extends between the third finger and thefirst finger; during the deforming step the at least two fingers areconverged towards the tube axis thereby forming a tapered shaft portion;each of the at least two fingers include an end portion, the endportions being brought into contact during the deforming step to forminga tip of the tapered shaft portion; during the joining step, the firstfinger is joined to the second finger through a portion of the firstlongitudinal opening by at least one binding, the second finger isjoined to the third finger through a portion of the second longitudinalopening by at least one binding, and the third finger is joined to thefirst finger through a portion of the third longitudinal opening by atleast one binding; each of the at least two fingers are joined to anadjacent finger through at least one of the plurality of longitudinalopenings by at least one binding at the tip of the tapered shaftportion; a plurality of bindings join at least two of the first finger,the second finger and the third finger through at least one of the firstlongitudinal opening, the second longitudinal opening, and the thirdlongitudinal opening; at least one finger includes a plurality of bossportions; further comprising the step of coating or bonding abrasivematerial to an external surface of the hollow instrument; furthercomprising the step of cutting the milled sheet to a desired shape; thechemically milling step is accomplished by photochemical machining; thepredetermined pattern defines a matrix formed of the plurality ofopenings that are at least partially bound by channels having an angledexterior surface; at least one finger includes a plurality of bossportions; the plurality of fingers include opposing side walls, eachopposing side wall having a plurality of boss portions; upon the atleast two free ends coming into contact, the plurality of boss portionsof a first finger and the plurality of boss portions of the secondfinger are positioned in a staggered relationship such that a bossportion of the first finger is positioned between two boss portions ofthe second finger; the plurality of fingers include a transverse widththat decreases towards the tip of the shaft; or any combination thereof.

It should be appreciated that the above referenced aspects and examplesare non-limiting as others exist with the present invention, as shownand described herein. For example, any of the above mentioned aspects orfeatures of the invention may be combined to form other uniqueconfigurations, as described herein, demonstrated in the drawings, orotherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A, is a perspective view of one embodiment of the presentinvention that includes a semi-finished hollow instrument (e.g., afterthe cutting step). The semi finished hollow instrument having aplurality of fingers (e.g., three fingers), which have been designed toallow the desired geometry in the finished shape (prior to the deformingstep). The shapes shown can be made using EDM, laser cutting, orconventional grinding.

FIG. 1B is an end view of the embodiment of FIG. 1 at the tip of thesemi-finished hollow instrument.

FIG. 1C is a top view of the embodiment shown in FIG. 1 showing endportions of the fingers that are angled from the exterior surfacetowards the interior surface such that the thickness at the end portiondecreases towards the end of the semi-finished hollow instrument (e.g.,tip portion) and showing the transition of the proximal end to the shaftportion where the fingers and longitudinal spacings of the shaft extendfrom the proximal end.

FIG. 2A is a perspective view of one embodiment of the present inventionthat resulting from the semi-finished hollow instrument shown in FIGS.1A-1C. The finished hollow instrument includes a plurality of deformedfingers that converge towards the tube axis e.g., (file axis) at thetip. After deformation of the fingers, the adjacent fingers are joinedthrough the longitudinal spacing therebetween by multiple bindings(e.g., welds) thereby securing the deformed fingers to provide a typicalendodontic rotary file taper. The joining of the fingers are provided atseveral locations along the taper. The individual finger welds can be atthe same distance from the tip creating a symmetrical file or atdifferent distances creating an asymmetrically flexible file. Weldsreduce the flexibility of the file locally. Generally more bindings(e.g., welds) result in less flexibility of the endodontic instrument.

FIG. 2B is an end view of the embodiment shown in FIG. 2A at the tip ofthe finished hollow instrument.

FIG. 2C is a zoomed-in perspective view of the embodiment shown in FIG.3 showing the multiple bindings spacedly positioned through each of thelongitudinal openings between each of the fingers.

FIG. 2D is a partial side view of the embodiments shown in FIGS. 2A-2Cwhile being deformed. The hollow instrument having multiple bindingsthough each of the longitudinal spacing to join the fingers therebyreducing flexibility caused by localized buckling of the hollowinstrument during deformation. It is believed that while in the rootcanal during a similar buckling of the lower finger, this reducedflexibility may cause the lower finger to deform inward towards the tubeaxis (e.g., file axis) thereby reducing cutting pressure locally orreducing finger contact with the root canal surface relative to asimilarly shaped sold file.

FIG. 2E is a partial zoomed-in side view of the embodiment shown inFIGS. 2A-2C while being differently deformed showing minimal deformationof a finger along one side of the hollow instrument relative tolocalized buckling of another finger along an opposing side of thehollow instrument.

FIG. 3A is a top view of another embodiment of the present inventionresulting from the semi-finished hollow instrument shown in FIGS. 1A-1C.This embodiment is similar to the embodiment shown in FIG. 2 but for theplurality of tapered fingers (e.g., three fingers) being interconnectedat a tip portion by a single weld across each longitudinal spacing toadjacent fingers (e.g., for this specific example, three total weld, onebetween each of the three fingers through each of the three longitudinalspacings).

FIG. 3B is a zoomed-in top view of the embodiment shown in FIG. 3A. Thefinished hollow instrument having multiple (e.g., three) fingerendodontic instrument having a single weld, which may enable one or morefingers (e.g., preferable each finger) to act independently of theother(s) and generally provides the maximum flexibility. The individualfingers with a small cross section are generally free to buckleindividually (though not required) when placed in a tightly curvedcanal.

FIG. 3C is a side view of the embodiments shown in FIGS. 3A-3B beingdeformed. The hollow instrument having a single weld proximal to the tipshows increased flexibility caused by localized buckling of the hollowinstrument during deformation. It is believed that while in the rootcanal during a similar deformation of the upper finger, this increasedflexibility may cause the upper finger to deform thereby adding cuttingpressure locally to the surface proximate to the deformed upper fingerrelative to a similarly shaped sold file.

FIG. 4 is a side view of a root canal and the embodiment with singlebindings shown in FIG. 3A showing the hollow instrument taking on agenerally S-shaped configuration in a canal as each finger actsindependently near the end of the longitudinal openings towards theproximal end of the hollow instrument. The lower finger is generallyfree to adapt to the shape of the canal thereby expanding (e.g.,deforming outward near the proximal end) and compressing (e.g.,deforming inward near the middle portion of the shaft) along differentportions of the lower finger.

FIG. 5 is a partial perspective view of another embodiment of a fingershown in FIG. 1A having multiple boss portions such as “teeth” (e.g.,sharpened teeth) extending from the opposing side walls of the finger.Advantageously, cutting efficiency may be increased utilizing the one ormore boss portions.

FIG. 6 is a partial perspective view of another embodiment of thesemi-finished hollow instrument shown in FIG. 1A having multiple bossportions such as “teeth” (e.g., sharpened teeth) extending from theopposing side walls of each finger. It is appreciated that during theforming step, the boss portions having sharp corners are cut out fromthe fingers while maintaining the integrity of the hollow instrumentgenerally intact. The corners may be generally spaced so that aclearance may be provided relative to one another when another fingermay be compressed.

FIG. 7 is a partial perspective view of another embodiment of thepresent invention that resulting from the semi-finished hollowinstrument shown in FIGS. 1A showing the individual fingers having theboss portions collapsed. The boss potions being in a staggeredrelationship such that the sharp corner of one boss portion along onefinger merges generally between two boss portions of an adjacent fingerto provide a series of cutting edges. The fingers may be welded intothis geometry creating a multi-sided, sharp, tapered hollow instrument.

FIG. 8 is a partial perspective view of another embodiment of thepresent invention resulting from the semi-finished hollow instrumentshown in FIGS. 1A. This embodiment includes a non-uniformly taperedhollow instrument having boss potions on each finger only along portionsof the shat near the tip. By shaping or curving the fingers (e.g.,pre-bent or pre-curved) prior to joining step the fingers may providemore radial force thereby cutting even more aggressively. Optionally,the sharp edges may extend the length of the fingers or be localized atany location along the one or more fingers to provide additional cuttingat various points along the endodontic hollow instrument (e.g., file).Therefore, the endodontic hollow instrument could provide moreaggressive cutting apically or coronally.

FIG. 9 is a partial perspective view of another embodiment of thepresent invention resulting from the semi-finished hollow instrumentshown in FIGS. 1A. This embodiment includes one finger that is longerthan and extends past the others fingers. The other (e.g., shorter)fingers may be joined to the longer finger by a least one binding at adistance from the tip. This may allow even more flexibility at the tipand the hollow instrument overall.

FIG. 10 is a partial perspective view of another embodiment of thepresent invention resulting from the semi-finished hollow instrumentshown in FIG. 1A. This embodiment includes helical cut fingers in thehollow instrument. The helical cut fingers may be joined by at least onebinding at the tip alone (as shown) or by multiple binding along one ormore portions of the longitudinal openings between adjacent fingers. Thehelical cut fingers may provide more flexibility along each helix.Optionally, sharp edges could be added (as shown previously) for moreaggressive cutting.

FIG. 11 is a partial top view of another embodiment of a semi-finishedhollow instrument in an unrolled orientation having multiple spacedopenings extending transversely (e.g., radially) through each taperedfinger. The multiple spaced openings of one finger being positioned in astaggered relationship relative to the adjacent fingers.

FIG. 12 is a top view of the semi-finished hollow instrument shown inFIG. 1A in unrolled orientation having tapered fingers that decreasetowards the tip and tapered longitudinal openings that increase towardsthe tip.

FIG. 13A is a perspective view of another embodiment of the presentinvention that includes a hollow instrument having a variable grooveextending along the hollow instrument. The variable groove having aseries of S-shaped curves that decrease in amplitude to accommodated thetaper of the hollow instrument. In one specific embodiment, the variablegroove may be cut into a tapered hollow tube.

FIG. 13B is a top view of a sheet material having the variable groovecut therein to defines series of the S-shaped curves. The groove may becut into the sheet material by lasers or otherwise or may be chemicallymilled (e.g., photochemically machined) to remove material. The sheetmaterial may be formed (e.g., shaped) according to a desired geometryprior to being rolled for forming a taper hollow instrument.

FIGS. 14A-14D are perspective top views of another embodiment of thepresent invention showing another process for forming a tapered hollowinstrument. The process included providing a sheet of material (e.g.,flat metal sheet). Photochemically machining the sheet material to havea desired pattern (e.g., geometry). The desired pattern being defined bymultiple channels at least partially bounding multiple openings (e.g.,diamond shaped openings). Stamping the sheet material having the desiredpattern to a desired shape (e.g., tapered shape). Rolling the stampedsheet to a desired tubular shape. Joining the ends of the rolled sheetto secure the rolled sheet in the desired tubular shape to form thetapered hollow instrument. It is appreciated that the edges of thechannels extending between an exterior surface and an interior surfacemay be configured for cutting.

FIG. 15A is a partial top view of the exterior surface of the patternedportion of the sheet material. The exterior surface having angledchannels therefrom. The angled portions may be configured as anothercutting surface in additions to the channels edges.

FIG. 15B is a partial top view of the exterior surface of the patternedportion of the sheet material. The channel portions having a generallyflat interior surface.

FIG. 15C. is a cross-sectional view of the embodiment shown in FIG. 15Ashowing the triangular cross-section of the channels.

FIGS. 16-21 are top views of various sheet materials having differentpatterns using in the process shown in FIGS. 14A-14D.

DETAILED DESCRIPTION OF INVENTION

This invention relates to dental instruments in general. Specifically,this invention relates to endodontic hollow instruments for use in rootcanal cleaning and shaping procedures. In general, the channels to bewidened and/or cleaned and/or shaped by the hollow instruments of thepresent invention are relatively long and narrow. The hollow instrumentscan be inserted completely to the end of a root channel or onlypartially into the channel, in which case only part of the channel willbe widened and/or shaped and/or cleaned. As an illustrative, butnon-limitative, example of the instrument of the invention embodimentsof an endodontic file for performing root canal treatments will bedescribed hereinbelow.

The present invention provides an innovation of endodontic instrumentthat may be made of shape memory alloys (SMA) such as Nickel-Titanium(NiTi) based systems, Cu based systems Fe based systems, or anycombination thereof (e.g., materials selected from a group consisting ofnear-equiatomic Ni—Ti, Ni—Ti—Nb alloys, Ni—Ti—Fe alloys, Ni—Ti—Cualloys, beta-phase titanium and combinations thereof), non-shape memoryalloys (e.g., stainless steel or otherwise, plastics, composites, or anycombination thereof.

The present invention employs methods for manufacturing endodonticinstruments (e.g., rotary files) from a sheet of material or a hollowmember such as a tube. The sheet of material and/or the hollow membermay be formed of Nitinol, stainless steel, other raw materials orcombinations thereof. Advantageously, in one embodiment, the amount ofmaterial removed during the manufacturing process may be reduced bystarting with a hollow shaped member (e.g., tubular shaped), optionallyformed of Nitinol. The hollow shaped member may be generally close tothe final desired shape of the endodontic instrument, thereby reducingthe amount of material that needs to be removed (e.g., from grinding orotherwise process(es)). The hollow members are generally readilyavailable in various lengths so as to enable mass production. In anotherembodiment, the sheet of material may be chemically milled to include adesired pattern of throughholes. The sheet material having the desiredpattern may be subsequently rolled to form the hollow instrument (e.g.,hollow endodontic file).

The preferred embodiment of the endodontic instrument of the invention,known herein as a hollow instrument (e.g., hollow file) that may be arotary or reciprocating instrument. While current leading rotary filesmay be limited to constant tapered diameters, the hollow file may beused as instrument capable of a variable taper. When inserted into anarrow canal, the instrument may compress allowing it reduced contactwith the walls of the canal in each radial plane along a portion of thelongitudinal axis of the canal thereby minimizing (e.g., reducing) canalwall removal relative to a file with a generally constant taper.Alternatively, or in addition to, the instrument may expand wheninserted into the narrow canal allowing it to adapt itself to thecross-sectional shape of the walls of the canal in each radial planealong a portion of the longitudinal axis of the canal so that contactwith the canal wall is increased thereby maximizing (e.g., increasing)canal wall removal relative to a file with a generally constant taper.It is appreciated that one or more portions of the hollow instrument maybe configured to compress in the radial plane along the shaft while oneor more different portions of the hollow instrument may be configured toexpand in the radial plane along the shaft. Finishing the hollowinstrument by any of several surface modifications (such as diamondcoating, vapor deposition, bead blast or otherwise) to have an improvedcutting surface or edge.

Rotating and/or reciprocating rotationally and/or axially in the canalthe hollow instrument removes tissue and debris from the canal and thecanal wall. Desirably, the hollow center void of the hollow instrumentmay provide a conduit for debris as it is removed from the canal wall.Furthermore, it is contemplated that the hollow center void of thehollow instrument may be configured as a conduit for providing asolution to the root canal such as for irrigation to aid in cleaningprocess of the root canal. For example, material scraped from the wallof the canal passes may pass through the spacings between the fingers ofthe shaft portion into the hollow void from which it can easily beremoved by rinsing or suction without stopping rotation and/orreciprocation of the instrument or withdrawing it from the root canal.In other embodiments, the debris can also be removed via the openingswith the matrix of the shaft portion or by the space between the canalwall and the instrument. The design discussed herein may allow forfluids, such as antiseptic or saline solution, to continuously flow intothe root canal, either through the center of the hollow instrument orbetween the outer surface of the hollow instrument and the canal wall,while the instrument is working, thus saving valuable time and improvingthe debridement and disinfection procedures. The constant flow alsoincreases the efficiency of filing and prevents clogging the canal withdentin-mud and debris. Another advantage of the hollow instruments isthat, in the extreme case of instrument failure and breakage inside thecanal, the separated part of the instrument of the invention can beeasily and safely removed, using specially designed extractors, nomatter what the position of the broken piece of the instrument in theroot canal.

After part of the crown is removed and the pulp is cleaned out of thepulp chamber, and a sufficient access to the canal is obtained, thehollow instrument is inserted into the root canal. As the hollowinstrument is pushed into the canal, its increased flexibility allows itto be guided to the apical end of the root canal by following the pathof least resistance (through the pulp rather than the much harderdentine). Prior art files can also adapt themselves to the canal shapelongitudinally but are unable to change their volume and contour as canthe hollow instrument of the present invention. Additionally the solidstructure of the prior art files makes them less flexible than thehollow shaped instrument designs described herein.

A first embodiment of the present invention includes a hollow instrument10 having an elongated shaft portion 12 with a proximal end 14 to whichmay be secured to an attachment end 16 for attachment to a handpiece(e.g., a rotary device). The shaft portion 12 (e.g., working portion) isconfigured to be inserted into and removed from the root canal of thetooth and includes a tip 114.

The hollow instrument 10 may be provided in various sizes having anywidth, length, and/or thickness sufficient for accommodating a dentalhandpiece and/or removing debris according to the present invention. Itis appreciated that the hollow instruments described herein may beformed having different lengths and/or various file tapers. For example,it is appreciated that the diameter may be reduced so that the shaftportion 12 includes greater than about 0% taper, preferably from about1% to about 10% taper, and most preferably from about 2% to about 6%taper.

The semi-finished hollow instrument 10 may further include a exteriorsurface 20 and an interior surface 22 defining a hollow center void 24at least partially bounded by a plurality of fingers 26. The fingers 26generally extend from the proximal end 14 to define the shaft portion 12and may be interconnected in the finished hollow instrument by at leastone binding. Examples of the binding may include, but is not limited to,welding (e.g., arc, ultrasonic, laser, resistance, extrusion, induction,vibration, spin, dielectric, microwave, or otherwise), soldering,brazing, frame joints, adhesive, cement, mechanical fasteners, (e.g.,nails screws, bolts, rivets, or otherwise) and otherwise or combinationsthereof. Each finger may include a pair of opposing side walls 28defining a finger width W therebetween and extend between the exteriorsurface 20 and the interior surface 22 to define a finger thickness. Theside walls 28 may form an edge, may be curved, flat, angled, orotherwise while extending from the proximal end 14, between the surfaces20,22, or a combination of both.

Preferably, the hollow void 20 may completely extend through theproximal end 14 (in addition to the shaft portion 12) generallylongitudinally along the tube axis (e.g., file axis) 25 therebyproviding a longitudinal throughhole, though not required.Alternatively, the hollow void may not extend through the proximal endsuch that the proximal end is not hollow (e.g., solid) or the hollowvoid may only partially extend through the proximal end generallylongitudinally along the file axis 24.

The semi-finished hollow instrument 10 may further include one or morespacings 30 extending between adjacent fingers 22 and from the proximalend 14 to the tip 114. As shown in FIG. 1A, as the finger widths (e.g.,distance between side walls 28) decreases towards the tip 18, the widthof the spacing between adjacent fingers increases towards the tip 114.However, it is appreciated that the fingers 22 may be formed of anyshape or size and may be the same or different. For example as shown inFIG. 9, finger 22′ is generally longer any may include a different(e.g., smaller) cross-section than the remaining fingers 22.

In another embodiment, the semi-finished hollow instrument 10 mayinclude one or more fingers 32 having boss portions 34 extending from atleast one side wall 28 (e.g., such as in a saw tooth arrangement). Theboss portions may be configured for aiding in the removal of debris(e.g., enhanced cutting). In one specific example as shown in FIGS. 5-7,the hollow instrument includes a first finger 36, a second finger 38,and a third finger 40 with each finger having multiple boss portionsextending outward (e.g., generally transversely from the fingers) fromboth opposing side walls 28. In this specific example, the boss portionsmay be positioned in a staggered relationship such that they aregenerally similarly spaced along each opposing wall 28, while beingoffset from one opposing wall relative to the other opposing wall. Asshown in FIG. 7, this staggered relationship allows for one boss portionof one finger to be positioned between two boss portions of an adjacentfinger. More particularly the boss portions 42 along the first opposingwall 44 of the first finger 36 are positioned respectively between theboss portions 46 along the second opposing wall 48 of the second finger38 and the boss portions 42 along the second opposing wall 50 of thefirst finger 36 are positioned respectively between the boss portions 52along the first opposing wall 54 of the third finger 40 while the bossportions 52 along the second opposing wall 56 of the third finger 40 arepositioned respectively between the boss portions 46 along the firstopposing wall 58 of the second finger 38.

It is appreciated that the respective boss portions may have a shapeand/or size that is the same or different along one or both opposingwalls of each finger or from one finger to another. Preferably the bossportions may be shaped to include an angle have a point such as atriangle, though others shapes are contemplated (e.g., curved such asovals, circles, squares, rectangles, or otherwise).

In another embodiment, the hollow instrument may include a variabletaper defined by one or more pre-bent fingers having at least one curveor bend (e.g., convex curve, concave curve or a combination of both). Inone specific example as shown in FIG. 8, a hollow instrument 60 includesa plurality of pre-bent fingers 62, each having a concaved curve 64. Thepre-bent fingers 62 extend longitudinally from the proximal end 14 whilebeing increasingly displaced from the file axis 25 so that theinstrument cross-section (e.g., diameter) may be increased. The ends 66of the pre-bent fingers 62 may be displaced towards the file axis 25(e.g., decreasing the instrument cross-section) thereby forming the tip68 of the hollow instrument 60. Preferably, the tip 68 may be positionedalong the file axis 25, though not required. It is appreciated that oneor more of the fingers 62 may further include boss portions 70 (e.g.,protrusions) along the entire finger or along one or more portionsthereof. In one specific example as shown in FIG. 8, each fingerincludes a plurality of boss portions 70 along a portion of the opposingwalls 72 that extends between the curve 64 (e.g., the apex of the curveor offset portion) and the end portion 66 of fingers 62.

Advantageously, instrument compression and/or expansion during removalof debris (e.g., material) may be increased in a hollow instrumenthaving a pre-bent configuration such as the hollow instrument 60. Forexample, it is appreciated that during the removal of the infected areaof the root canal 74 and surrounding area (FIG. 4), the hollowinstrument may typically encounter some resistance as portions of thefingers contact the material to be removed (e.g., dentin, pulp, nervetissue and/or infected material) within the tooth. This instrumentresistance and optionally any downward force by the operator towards theapex of the root canal during use of the hollow instrument, may causethe finger portions to expand (e.g., generally increase fingerdisplacement from the file axis), collapse (e.g., generally decreasefinger displacement from the file axis), or a combination of both.Expansion and/or collapsing of one or more portions of the fingersgenerally may occur in the transverse (e.g., radial) direction, thelongitudinal direction, or a combination of both relative to the fileaxis so that surface contact with the root canal (e.g., the material tobe removed) may be increased. More particularly, as the instrumentresistance occurs (e.g., contacting the dentin and/or root canal wall)one or more portions of the fingers may be deformed along a path ofleast resistance (e.g., towards the pulp material) so that dentinremoval may be minimized while maximizing contact with the pulp materialthereby maximizing pulp material removal.

FIGS. 2D-2E show the hollow instrument 116 that has been deflected(e.g., bent) upon contact with a surface 76. The hollow instrument 116includes a plurality of fingers being interconnected by a plurality ofbindings 112. The plurality of fingers and selective placement of thebindings 112 cooperate to allow for increased deflection of the hollowinstrument 116. For example, as the shaft portion 80 is deflecteddownward, the plurality of fingers may be compressed (e.g., decrease inthe instrument cross-section relative to the instrument cross-section ina non-deflected state) such that a first finger 82 is displaced towardsthe other fingers 84 thereby allowing improved flexibility of the hollowinstrument 116. In doing so, the hollow instrument 116 may be furtherdeflected (e.g., bent) to increase adaptation of hollow instrument tothe cross-section of the root canal relative to a similarly formed solidinstrument. By increasing flexibility (e.g., adaptation to the rootcanal), the hollow instrument may be configured to increase removal ofpulp material while decreasing removal of dentin material. It isappreciated that the deflection of the shaft portion 80 is forillustration purposes only and similar instrument compression resultsmay occur upon deflection of the shaft portion 80 in other directions.

It is appreciated that the hollow instruments described herein may notrequire binding to maintain the hollow instrument in its desired shape.This may be dependent on the deformation or thermal shape settingnecessary to maintain the desired geometry.

Furthermore, FIG. 3C show the hollow instrument 86 that has beendeflected (e.g., bent) upon contact with a surface 88. The hollowinstrument 86 includes a plurality of fingers being interconnected by atleast one binding 87 (though not required) proximate to the tip 89. Theplurality of fingers and selective placement of the binding 87 cooperateto allow for increased deflection of the hollow instrument 86. Forexample, as the shaft portion 90 is deflected upward, the plurality offingers may be expanded (e.g., increase in the instrument cross-sectionrelative to the instrument cross-section in a non-deflected state) suchthat a first finger 92 may be displaced outwards away from the otherfingers 94 thereby allowing improved flexibility of the hollowinstrument 86. In doing so, the hollow instrument 86 may be furtherdeflected (e.g., bent) to increase contact of hollow instrument to thesurface of the root canal relative to a similarly formed solidinstrument. By increasing flexibility and allowing for instrumentexpansion, the hollow instrument 86 may be configured to increasesurface contact of the root canal wall thereby increasing removal ofmaterial. It is appreciated that the deflection of the shaft portion 90is for illustration purposes only and similar instrument expansionresults may occur upon deflection of the shaft portion 90 in otherdirections.

In another embodiment, the present invention may include a hollowinstrument 96 having a shaft portion 97 including a plurality of twistedfingers 98 that define a hollow void 99 therebetween. The fingers 98being interconnected by at least one binding proximate to the tip 100.Optionally, the fingers 98 may include a first finger 99 that extendthrough the hollow void 101 to an opposing side of the shaft portion 97thereby contacting at least one different finger 103. When included, theplurality of fingers 98 may be interconnected by a plurality of bindings105.

The twisted fingers 98 extend longitudinally from the proximal end 14while being increasingly displaced from the file axis 25 so that theinstrument cross-section (e.g., diameter) may be increased. As thefingers 98 extend from the proximal end 14, each finger may be rotatedthereby forming a spiral (e.g., a helical having clockwise and/orcounter clockwise rotations). It is appreciated that each finger 98 mayform at least one spiral having a rotation of at least one at leastabout 5 degrees, preferably at least about 30 degrees, and morepreferably at least about 90 degrees. Furthermore, each finger may format least one spiral having a rotation of less than about 360 degrees,preferably less than about 315 degrees, and more preferably less thanabout 270 degrees. For example, each finger may form at least one spiralhaving a rotation ranging from about 5 to about 360 degrees, preferablyfrom about 30 to about 315 degrees, and more preferably from about 90 toabout 270 degrees. Desirably each finger includes a plurality ofspirals.

It is appreciated that the hollow instruments discussed herein mayfurther include or alternatively include one or more of the followingfeatures: a tapered fingers 101 including one or more openings 102extending from the exterior surface to the interior surface (FIG. 11);fingers having a body portion 104 with generally constant width and atapered end portion 106 (FIG. 12); fingers interconnected by multiplebindings 108, the fingers defining a hollow void 108 extending throughthe tip 110 (FIG. 2B); fingers interconnected by multiple bindings 112having an end binding 112 to define a bound tip 116 such that there isnot a hollow void extending therethrough (FIG. 2A).

In another embodiment, the present invention may include a hollowinstrument 118 having an elongated shaft portion 120 with a proximal end122 to which may be secured to an attachment end (or a handle) forattachment to a handpiece (e.g., a rotary device). The shaft portion 120(e.g., working portion) may be configured to be inserted into andremoved from the root canal of the tooth and includes a tip 124. Theshaft portion 120 (and optionally the proximal end 122) defines a hollowvoid 126 extending therethrough to the tip 124. The hollow instrument118 may further include at least one groove 128 extending longitudinallyfrom the proximal end 122. The groove 128 further extends radiallybetween an exterior surface 130 and an interior surface 132 and includesa width extending between opposing walls 134. The opposing walls 134 maybe curved, flat, angled, or otherwise. The groove 128 may be in generalcommunication with the hollow void 126. The groove 128 may be acontinuous groove or part of multiple grooves and may be defined byvarious shapes and/or sizes. As shown in FIGS. 13A-13B, the groove 128extends from the proximal end 122 to the tip 124 and includes agenerally decreasing width towards the tip 124, however a constant widthis also appreciated. The groove 128 may be include multiple curveportions 134 (e.g., S-shaped portions or otherwise) of decreasingamplitude to accommodate the taper of the hollow instrument 118. Thecurve portions 134 of the groove 128 generally define projections 136formed by the opposing walls 134 and the exterior and interior surfaces130,132. The projections 136 and the opposing walls 134 provide acutting edge for removal of material. In one specific embodiment, theprojections 136 may include a head portion 138 and a neck portion 140(e.g., being integrally connected to the shaft portion 120), the headportion 138 having a width greater than the neck portion 140. It isappreciated that the head portion 138 may be a generally curved orarcuate shaped portion, though not required.

In another embodiment, the present invention may include a hollowinstrument 142 having an elongated shaft portion 144 with a proximal end146 to which may be secured to an attachment end (or a handle) forattachment to a handpiece (e.g., a rotary device). The shaft portion 144(e.g., working portion) may be configured to be inserted into andremoved from the root canal of the tooth and includes a tip 148. Theshaft portion 144 (and optionally the proximal end 146) may define ahollow void 150 extending therethrough to the tip 148. The shaft portion144 includes an exterior surface 152, an interior surface 154 that atleast partially defines the hollow void 150, and a matrix 156 formedfrom a plurality of openings 158 extending at least partially throughthe shaft portion 144. Preferably, the matrix 156 includes a pluralityof openings 158 that extend from the exterior surface 152 to theinterior surface 154 thereby forming a throughhole in communication withthe hollow void 150. The matrix 156 further includes channels 160extending between the exterior and interior surfaces 152, 154 and theopenings 158. The channels 160 may be flat, angled, curved, or otherwiseand any combination thereof. The openings 158 may be formed in variousshapes (e.g., squares, rectangles, diamonds, triangles, circles, otherpolygonal shapes, or otherwise shapes) and/or sizes. The matrix 156 mayinclude openings 158 that are the same or different.

The present invention may further include a process of producing ahollow instrument (e.g., dental instrument such as an endodontic file).The method for forming the hollow instrument may include one or more ofthe following steps and combinations thereof: Providing a hollow tube(e.g., a medical tube such as a hypodermic needle tube) beingdimensioned generally similar to the desired finished size of the hollowinstrument. Cutting the tubing wall (e.g., using laser cutting or waterjet cutting, or otherwise) following a predetermined pattern. Desirably,the predetermined pattern cut into the hollow tube may form at least oneand preferably several abrasive cutting edges to achieve desired cuttingproperties. Deforming the hollow tube into a desired final shape.Joining (e.g., binding) portions of the cut pattern along the hollowtube to form the hollow instrument. Finishing the hollow instrument byany of several surface modifications (such as diamond coating, vapordeposition, bead blast or otherwise) to have an improved cutting surfaceor edge.

In a specific example, the present invention may provide for a method ofmanufacturing the endodontic instrument including one or more of thefollowing steps and combinations thereof: 1) The rotary file is madeusing hollow tubing of the desired finished size. 2) The tubing wall iscut (using laser cutting or water jet cutting for example) following apattern of the desired final shape. The pattern cut in the tube cancreate any of several abrasive cutting edges to achieve the desiredcutting properties. 3) The tubing is deformed to the desired finalshape. 4) The tubing is joined (by means of welding for example) atpoints along the cut pattern to form the desired final shape. 5) Thefinished part can then be altered by any of several surfacemodifications (such as diamond coating, vapor deposition, bead blast) tohave an improved cutting surface or edge. An embodiment of the rotaryfile includes tapered cut longitudinal members which meet at the distalend to form a standard tip size and taper. Another embodiment would be acurved and circumferential pattern around the tube which would enable afinal shape that has helical members. The resulting geometry eliminatesthe core of the rotary file and improves file flexibility and provides avoid for movement of debris during root canal therapy.

As discussed herein, it is appreciated the joining step may be optionaland that the deformation step alone may be sufficient to maintain thedeformed tube in its desired shape. For example, by forming in the caseof stainless steel or thermal shape setting by temperature in the caseof a NiTi.

It is appreciated that the hollow tube may be provided as a solid objectthat may be bored out to form the hollow void therein. The hollow voidmay extend longitudinally through the entire length of the tube or mayextend longitudinally through only a portion thereof (e.g., only throughthe portion that may become the shaft portion.

The present invention may further include another process of producing ahollow instrument (e.g., dental instrument such as an endodontic file).The method for forming the hollow instrument may include one or more ofthe following steps and combinations thereof: Providing a sheet ofmaterial (e.g., metal sheet, plastic sheet, or otherwise andcombinations thereof). Chemically milling (e.g., photochemicallymachining or photo etching) the sheet to remove material following apredetermined pattern. Desirably, the predetermined pattern milled intothe sheet may form at least one and preferably several abrasive cuttingedges to achieve desired cutting properties. Rolling the patterned sheetinto a desired tubular geometry to form a hollow tube. Joining (e.g.,binding) portions of the hollow tube to secure the hollow tube into thedesired tubular geometry thereby forming the hollow instrument.Finishing the hollow instrument by any of several surface modifications(such as diamond coating, vapor deposition, bead blast or otherwise) tohave an improved cutting surface or edge.

In one specific example, a sheet material 162 may be provided in astandard geometry (e.g., square, rectangular, or otherwise) as shown inFIG. 14A. A predetermined pattern 164 may thereafter be chemicallymilled into the standard geometry sheet 162 to form a patterned sheet166 as shown in FIG. 14B. The patterned sheet may be shaped (e.g., bystamping, shape setting, or otherwise) into a desired geometry to form ashaped patterned sheet 168 as shown in FIG. 14C. The shaped patternedsheet 168 may be rolled into a desired tubular geometry to form a hollowtube (e.g., tapered hollow tube). The hollow tube may be joined (e.g.,welded or otherwise) to secure the hollow tube into the desired tubulargeometry thereby forming a hollow instrument 170 as shown in FIG. 14D.It is appreciated that the sheet material may be provided in a desiredshaped geometry prior to the chemically milling step thereby possiblyrendering the forming step thereafter unnecessary.

The present invention may provide another embodiment including thehollow instrument 170 formed from the process described above. Thehollow instrument 170 may include a matrix 172 generally defined by thepredetermined pattern 164. The matrix 172 may include channels 174defining openings 176 having a diamond (e.g., square) shaped pattern. Inone specific example, the channels 174 include an angled exteriorsurface 178 and a generally flat interior surface 180 as shown in FIGS.15A-15C. It appreciated that the exterior surface and/or the interiorsurface may have a slight curve resulting from the overall hollow shape(e.g., tubular cone shape) of the hollow instrument. Desirably, thecross-section of the channels 166 may be generally triangularly shaped,though not required.

FIGS. 16-21 will now be discussed. Various patterns may be chemicallymilled into the sheet material 162 thereby forming openings havingcircle shapes 182 (FIG. 16), triangle shapes 184 (FIG. 17), similarshapes (e.g., square, diamond, or otherwise shapes) of different sizes186,188,190 (FIG. 18), a plurality of shapes including a plurality ofsimilarly sized first shapes 192 (e.g., squares or otherwise) and aplurality of similarly sized second shapes 194 (e.g., triangles orotherwise), the first shapes 192 being different from the second shapes194 (FIG. 19), different shapes of various sizes 196,198,200 (FIG. 20),elongated rectangle shapes 202 (FIG. 21), or otherwise, and anycombination thereof.

The sheet material and/or the perimeter wall defining the hollow tubemay include a contact thickness or a variable thickness. When included,the thickness may vary such the hollow instrument may have a thickerperimeter wall at the proximal end relative to the tip end or a thinnerperimeter wall at the proximal end relative to the tip end, It iscontemplated that the perimeter wall may include a variable thicknesswith a constant taper. Preferably the perimeter wall includes a contactthickness at least throughout the shaft portion of the hollowinstrument.

It is appreciated that as the hollow instrument rotates, reciprocatesand/or axially moves, its cross-sectional shape may be constantlychanging to conform to the shape of the canal wall and the length of thecircumference of the device in that plane may be constantly increasingas material is removed from the wall. This is to be compared to thesituation with existing files in which the shape of the canal is changedto conform to the shape of the file and the files must constantly bereplaced with files of larger diameter in order to clean, widen, andshape the canal.

The advantages to this new type of rotary hollow file design as comparedto conventional rotary solid files may be that the new design may changegeometry when forces are exerted upon it. This may allow for optimumcleaning and shaping of the root canal. Since most root canals are notexactly conic in shape, typically the dentist will either have to removemore of the dental structure than desired to ensure that they haveremoved all of the bacteria or will remove less than desired to preservethe root structure but this will not allow all of the bacteria to beremoved. This design takes it a step further though in its developmentfor three main reasons. The present invention may utilize an alternativeprocess called Photochemical Machining (also known as Photochemicalmilling or Photo etching). The process includes fabricating sheet metalcomponents using a photoresist (light sensitive material) and etchantsto corrosively machine away selected areas. One of the main benefits toPhotochemical machining may be that the tooling is inexpensive andquickly produced and it can make a part in hours after receiving thedrawing. Furthermore, it is appreciated that the Photochemical machiningprocess may allow for a variable cross-section. With Photochemicalmachining, it allows for a variable cross-section where one side isaggressive for cutting while the other side is wider and not aggressivefor structure stability.

It will be further appreciated that functions or structures of aplurality of components or steps may be combined into a single componentor step, or the functions or structures of one-step or component may besplit among plural steps or components. The present inventioncontemplates all of these combinations. Unless stated otherwise,dimensions and geometries of the various structures depicted herein arenot intended to be restrictive of the invention, and other dimensions orgeometries are possible. In addition, while a feature of the presentinvention may have been described in the context of only one of theillustrated embodiments, such feature may be combined with one or moreother features of other embodiments, for any given application. It willalso be appreciated from the above that the fabrication of the uniquestructures herein and the operation thereof also constitute methods inaccordance with the present invention. The present invention alsoencompasses intermediate and end products resulting from the practice ofthe methods herein. The use of “comprising” or “including” alsocontemplates embodiments that “consist essentially of” or “consist of”the recited feature.

The explanations and illustrations presented herein are intended toacquaint others skilled in the art with the invention, its principles,and its practical application. Those skilled in the art may adapt andapply the invention in its numerous forms, as may be best suited to therequirements of a particular use. Accordingly, the specific embodimentsof the present invention as set forth are not intended as beingexhaustive or limiting of the invention. The scope of the inventionshould, therefore, be determined not with reference to the abovedescription, but should instead be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. The disclosures of all articles and references,including patent applications and publications, are incorporated byreference for all purposes.

What is claimed:
 1. A hollow endodontic instrument comprising: a fileaxis; a proximal end; a tip; and a shaft portion between the proximalend and the tip; wherein the shaft portion defines a hollow void atleast partially bounded by a plurality of fingers and a plurality oflongitudinal spacings, each finger extends from the proximal end andincludes an outer surface and an inner surface extending betweenlongitudinal opposing walls; and wherein a portion of at least one ofthe longitudinal opposing walls includes a cutting edge.
 2. The hollowinstrument of claim 1, wherein the plurality of fingers converge at thetip such that there is contact between at least two fingers for joiningto one another by at least one binding.
 3. The hollow instrument ofclaim 1, wherein at least one finger includes a plurality of bossportions.
 4. The hollow instrument of claim 3, wherein each opposingside wall includes a plurality of boss portions.
 5. The hollowinstrument of claim 4, wherein upon at least two fingers coming intocontact, the plurality of boss portions of a first finger and theplurality of boss portions of a second finger are positioned in astaggered relationship such that a boss portion of the first finger ispositioned between two boss portions of the second finger.
 6. The hollowinstrument of claim 1, wherein the plurality of fingers include atransverse width that decreases towards the tip of the shaft.
 7. Thehollow instrument of claim 1, wherein a first longitudinal spacingextends between a first finger and a second finger, a secondlongitudinal spacing extends between the second finger and a thirdfinger, and a third longitudinal spacing extends between the thirdfinger and the first finger.
 8. The hollow instrument of claim 7,wherein a plurality of bindings join at least two of the first finger,the second finger and the third finger through at least one of the firstlongitudinal spacing, the second longitudinal spacing, and the thirdlongitudinal spacing.
 9. The hollow instrument of claim 1, furthercomprising a coating of abrasive material to an external surface of thehollow instrument.
 10. A hollow endodontic instrument comprising: a fileaxis; a proximal end; a tip; and a shaft portion extending between theproximal end and the tip, the shaft portion defining a hollow void atleast partially bounded by a matrix of channels and a plurality ofopenings therebetween, the matrix extending from the proximal end andconverges at the tip; wherein each channel includes opposing edges andat least a portion of at least one of the opposing edges includes acutting edge.
 11. The hollow endodontic instrument of claim 10, furthercomprising a coating of abrasive material to an external surface of thehollow instrument.
 12. The hollow endodontic instrument of claim 10,wherein the plurality of openings extend from the exterior surface tothe interior surface thereby forming a throughhole in communication withthe hollow void.
 13. The hollow endodontic instrument of claim 10,wherein the plurality of openings has a shape selected from the groupconsisting of squares, rectangles, diamonds, triangles, and circles. 14.The hollow endodontic instrument of claim 13, wherein the plurality ofopenings are different is shape and/or size.
 15. The hollow endodonticinstrument of claim 10, wherein the channels include an angled exteriorsurface and a generally flat interior surface extending between theopposing walls.